First the specific question then the application:
The datasheet specifies channel-channel match as +- 0.05dB.
It is not clear to me whether this holds when the gains of both channels are identical, or whether it holds over all gain combinations of both channels.
Now the application:
Our application requires measuring the relative signal levels (gain) between two inputs (say A and B) as precisely as possible.
Each of A and B is a sine wave with amplitude ranging over 3 orders of magnitude, say 1mV to 1V (but can be scaled as desired).
In spite of the above, at any particular time, signal B is never less than 0.2 * signal A.
Ideally we would like the gain between the RMS of each signal, but gain between amplitudes may also be OK.
Frequency of both A and B is always identical, and can range between 5-100 MHz (but frequency at time of measurement is unknown).
The question regarding LMH6517 arose since one idea was to use a dual VGA in order to bring both A and B to approximately the same level and then do some fine correction.
I am open to any better suggestions.